Lubricating oil



Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE Lunarcs'rmG on.

Stiles Moxley Roberts, Beacon, N. Y., amt, by mesne assignments, to TheTexas Company, New York, N. Y., a corporation of Delaware No Drawing.Application January 15, 1941,

Serial No. 374,477

Claims. (Cl. 252-47) lubricating surfaces, particularly betweenthepiston and cylinder walls, and operate atmuch higher enginetemperatures. Also, the

resulting higher bearing pressures, increased ro-' tative speeds, andthe like, have necessitated a departure from the use of the usual bearinmetals, such as babbitt, and require harder alloy hearings or the typeof cadmium-silvencopperlead, cadmium-nickel, and the like.

These changes in-engine design have been concurrent with the developmentof solvent-refined lubricating oils wherein the viscosity index andother desirable features of the oils have been greatly improved byrefining the oils by certain solvent-refining or solvent extractionprocesses.

It has been found, however, that when these solvent-refined lubricatingoils are used in the crankcase of the improved engines they develop acarbonaceous deposit upon the metal surfaces. This deposit appears as ayellowish or reddish brown film and is most prevalent upon the pistonrings, piston skirt and cylinder walls. Over extended periods ofoperation this deposit may become so extensive as to clog the oil rings,fill up the oil lines, and build up on the piston and cylinder walls tosuch an extent as to eventually result in seizure of the piston when theengine is stopped and allowed to cool.

Upon close examination this carbonaceous deposit has been found toconsist of two components which may be difierentiated by theirsolubility in acetone. The portion of the deposit soluble in acetone hasbeen termed the varnish'? component, while the insoluble portion istermed the "lacquer" component. 1

Other undesirable features have become apparent in the lubrication ofthe new alloy bearings of the cadmium-silver, copper-lead,cadmium-nickel type with these solvent-refined lubricating oils. Thesealloys are'very susceptible to chemical attack andtheir use at hightemperatures, high speeds, and high pressures,

is usually accompanied by an accelerated de-,-

terioration of the lubricant and a highly corrosive reaction. It isquite possible'that the metals present in the bearings promotethe deare,in turn, attacked by the deterioration products. Whatever theexplanation of this deterioration and corrosive reaction maybe, theresulting sludge formation within the oil and etched or corrodedbearings may seriously sheet the eiliciency of the engine.

These problems, together with other problems involving the stability ofthe oils in storage and service oxidation changes, acid formation,viscosity changeasludging, and the like, have been met by theincorporation of various "addition agents in the refinedhydrocarbon'oils. Under these addition agents may be listed "antioxidanagents, stabilizing agents, anti-corrosion" agents, and the like. Theutility of these agents ,has been investigated in the laboratories andunder service conditions, and, in many their particular proposed use.

lo However, as pointed out above, the problems involved in thelubrication of internal combustion engines are not singular but ratherinpresence of other agents. Furthermore, each agent must be added in adefinite amount to be eflective, and when two or more agents are addedtogether in their individual critical amounts, the

physical properties and the remaining desirable features of theresulting oil usually are altered and, in most cases, to an undesirableextent.

The particular problems of varnish and lacquer formation, bearingcorrosion, and deterioration or sludge formation, are generallyconsidered to be the most serious in their effect upon the operation ofinternal combustion engines, especially Diesel engines, and it is upon asolution to these problems that the present invention is primarilyconcerned. However, in considering these particular problems, suchincidental problems as color stability, stability in storage andservice. resistance to oxidation, and the like, must also be kept inmind.

According to the present invention, it has been discovered that amineral lubricating oil of the tion, by the incorporation therein of asmall.

proportion of an oil-soluble neutral or basic terioration of the oils bya catalytic reaction and co p bvalent metal salt of an organic ester ofa phosphorus acid. It is to be understood that the term "organic esteris to include particularly the alkyl and naphthenyl esters and mixturesthereof, and the term phosphorus acid is meant to include the acidderivatives of the following phosphorus oxides:

Pro-phosphorus monoxide Pam-phosphorus trioxide P2O4phosphorus tetroxidePam-phosphorus pentoxide The alkyl ester may be either straight orbranched chain monoor di-alkyl esters containing, in the case of amono-ester, at least five and up to eighteen carbon atoms and, in thecase of the di-alkyl esters, at least nine carbon atoms taken incombination as, for example, methyloctyl or di-amyl esters. Thenaphthenyl esters embodiedherein are derived from naphthenyl alcoholswhich are obtained by the carboxylic reduction of naphthenic acids andtheir esters and contain at least six and not more than eighteen carbonatoms.

Examples of the specific compounds within this group which have beenfound especially suited to the purposes of the invention are calciumisoamyl octyl ortho phosphate and calcium octyl pyro phosphate. Amongthe metal salts which have been found to be particularly effective arethe calcium, magnesium, barium, tin, antimony, cobalt, aluminum, cadmiumand zinc salts. Similarly, other organic esters falling within the classoutlined above may be used, and include such monoalkyls as the amylhexyl, heptyl, octyl, etc., esters, together with their correspondingalkylated de-, rivatives and isomers. Also such di-alkyls as thepropyl-amyl, butyl-hexyl, propyl-octyl, amylhexyl, di-amyl, di-hexyl,etc., esters, together with their alkylated derivatives and isomers, maybe used. The phosphorus acids are inclusive of the ortho, meta, and hypophosphorous acids, and the ortho, meta, pyro, and hypo phosphoric acids.

This particular class of compounds may be prepared either by a directneutralization of the phosphorus acid organic ester with a metal oxideor by a double decomposition reaction. In the particular case of calciumisoamyl octyl ortho phosphate, 50 grams of isoamyl octyl ortho phosphateare dissolved in 250 cc. of benzol and to the resulting solution aslurry of 10 grams of calcium oxide in 25 cc. of ethyl alcohol is added.The resulting mixture of calcium oxide and isoamyl octyl ortho phosphateis then refluxed for three hours and the reaction mass filtered throughFilter-Gel. At this point it may be mentioned that any aromatic rparaflinic solvent, such as toluol, xylol or naphtha may be used in theplace of benzol and the calcium oxide may be added directly without theuse of alcohol. Upon removal of the solvent from the filtrate, 50 gramsof a light-brownish-yellow, resinous mass was obtained which could becrushed to a powder. The product was found to be directly soluble in alubricating oil and a concentrate prepared by dissolving the product inbenzol, then mixing the required amount of lubricating oil, withsubsequent removal of the solvent, was found to be very desirable inmaking blends. In the case of tin or antimony salts, the neutralizedproduct is best obtained by double decomposition of the solid salt witha sodium salt solution.

These described compounds are incorporated in the lubricating oil inproportions ranging from 0.05-5.0% by weight, depending upon the type oflubricant used. The preferred range of proportions in a lubricatingmotor oil is between 0.05 to 2.0%; in 9. Diesel lubricant from 0.05 to5%; and in an aircraft lubricating oil from 0.05 to 3.0%.

It has been found that when lubricating oils containing a smallproportion of the above-mentioned compounds are put to service tests,they not onlyminimize the lacquer and varnish for-- mation, bearingcorrosion, and sludge formation, but also possess unique detergentproperties. The heretofore known addition agents have been used only asinhibitors of a particular undesirable feature of the lubricating oil,and it has not been attempted to remove the eflects of the oil on theengine as in the case of varnish and lacquer deposits. However, theproposed additives not only inhibit but also act as a detergent inremoving any varnish or lacquer deposits which might be present on thelubricating surfaces prior to the use of these additives in thelubricating oil. In this way, an engine which has lost its power andefficiency by reason of the increased resistance, due to a varnish andlacquer formation, may be restored to its normal operation through theuse of a lubricating oil containing the proposed additives. As anexplanation for the detergent action of these additives it has beensuggested that, due to the high operating temperatures of the engines,the additive breaks down to the heavy metal phosphate or phosphite whichis in itself an excellent detergent. Whatever the explanation may be, ithas been found that an engine lubricated with a compounded oil asdescribed is not troubled with any varnish or lacquer formation on itspiston or cylinder walls.

Another feature of the present invention is the combination of thepreviously described additives with a corrosion inhibitor from the classof sulphurized fatty materials and the incorporation of smallproportions of this combination in a lubricating oil. This particularclass of compounds has already been acknowledged as possessing excellentanti-corrosion properties per se, and, when used in combination with theproposed additives of the present inventiomthese properties are notdiminished but rather are added to the effective properties of the otheradditive. As was previously discussed above, the combination of two ormore improving agents does not necessarily imply an additive effect and,in most cases, tends to destroy the improving qualities of theindividual agents.

Among the particularly effective sulphurized fatty materials foundsuitable for the purposes of this invention are those sulphurized fattymaterials formed by the sulphurization of non-glyceride fats, such aslanolin and sperm oil, or mixtures thereof. The amount of sulphurizedcompound added to a. lubricating oil in combination with the otheradditive is usually within the range of 0.05 to 5.0% by weight, andpreferably around 3.0%, depending upon the type of lubricating oil used.

These sulphurized fatty materials may be prepared in accordance with thecopending applicationse of Edwin C. Knowles and Frederic C. Mc- Coy,Serial Nos. 358,876 now issued as Pat. No. 2,289,437 of July 14, 1942,358,877 now issued as Pat. No. 2,289,438 of July 14, 1942, and 358,878,wherein a light-colored, sulphurized fatty material is prepared by thedirect addition of sulphur to the fatty material at approximately 300tion and lasts usually from one-half to three hours. The sulphurizedproducts formed by this process are directly soluble in lubricating oiland possess the added advantage in that the reaction product is alight-colored compound as against the usual dark-colored sulphurizedcompounds.

As illustrative of the unusual corrosion inhibiting properties of alubricating oil containing either or both of the aforementionedadditives, the results of the following empirical test are presented. Acopper-lead bearing specimen, incased in a special non-wear bushing androtatably mounted on a stainless steel shaft, was immersed in a glasspot'of the oil to be tested. The tested oil was heated to a controlledtemperature of either 250 F. or 350 F. and continuously circulatedbetween the bearing specimen and the shaft for periods of time varyingfrom two to ten hours. The bearing specimen was weighed before the testand at two-hour intervals and the loss in weight recorded in milligrams.The reference oil which was used throughout this test was asolvent-refined dewaxed Mid-Continent lu- 'bricating oil distillate ofan S. A. E. 30 grade.

To this reference oil was added varying proportions of the additives ofthe present invention, taken individually and in combination, and theresults compared. The results of two runs at 250 F. and 350 F.,respectively are presented:

Corrosion test (250 F.)--copper lead bearings [Bearing weight loss,mgs.]

Oil tested 2 hrs. 8 hrs. 10 hrs.

Ref. oil 9,12 16.19 2225 27,31 Ref. oil 0.5% calcium isoarnyl octylortho phos- 2 3 Corrosion test (350 F.)-copper lead bearings [Bearingweight loss, rugs] Oil tested 2 hrs. a hrs. 6 hrs. 8 hrs. 10 hrs.

A further illustration of the corrosion inhibiting properties of theadditives of the present invention was demonstrated by practical testsin a standard Plymouth engine equipped with special coarse structurecopper-lead bearings which were chosen for this test because of thelarger weight losses experienced under normal operation. This test wascarried out by running the 'phurized non-glyceride fat and engine fortwenty-four hours at 3000 R. P. M. with three-quarter open throttledeveloping about thirty-four brake horsepower with the crankcase oiltemperature maintained at 300 F. by means of an external heat exchangerwith an external pump, and with a water jacket temperature of 212 F. Thehearings were disassembled, cleaned and weighed before and after eachrun and the results tabulated as the percentage weight loss differencebetween the experimental oil and the reference oil. The reference oilin'this test was a solvent-refined dewaxed Mid-Continent lubrieating,oil distillate of S. A. E. 30 grade and was compared to the same oilcontaining 3.0% sul- 0.5% calcium isoamyl octyl ortho phosphate. Theresults obtained show 78% less bearing weight loss with the compoundedoil than with the reference oil taken on an average of two test runs.

In order to illustrate the aforementioned detergent properties of theadditives of the present invention, e. g. the ability of the compoundedoil to remove a deposit of varnish and lacquer from the surfaces of anengine piston and cylinder, a test was devised which simulated asclosely as possible the actual operating conditions of an internalcombustion engine. This test was conducted on a single cylinder standardLauson engine and the results obtained evaluated by visual inspectionaccording to a classification of bad, fair and good. A heavy va nishdeposit was obtained upon the piston of the Lauson engine by utilizing asolvent-refined, dewaxed Mid-Continent lubricating oil of an S. A. E. 10grade, and running the engine at 1800 R. P. M. with a jacket temperatureof 212 F., a crankcase temperature of 300 F... and with a crankcaseventilation of 0.4 cubic feet of air per minute for twenty-four hours.Then, without cleaning the piston, the oil was changed to the compoundedoil containing the proposed additives and the engine operated at 1800 R.P. M., with a jacket temperature of 315 F., a crankcase temperature of200 F., and with no crankcase ventilation for twenty-iour hours. At theend of the twenty-four hour perled the engine was dismantled, thecondition of the piston noted, and the oil classified. The followingresults were obtained with a, reference oil Oil tested Rating RemarksReference oil Bad.-. Heav varnish Reference oil-+30% sul nurized ydepsit' non-glyceride lat 0.5 calcium isoamyl octyl ortho phosphate...Fair... Light varnish film.

The efiect of the proposed additives in reducing oil ring sludge isshown by the results of a so-called oil ring sludge test. In this testa. CFR Diesel engine was operated for thirty-six hours at 1200 R. P.011., with a jacket temperature of 210 F. and a rich fuel mixture fed atthe rate of 20 cc. per minute to aggravate sludge formation. The runsfrom the test were first made by using a reference oil. such as asolvent-refined,

dewaxed Mid-Continent lubricating on S. A. E.

30 grade, and then, upon the same reference oil, compounded with varyingproportions of the proposed additives. At the completion of each run theoil rings were taken out and weighed, and the results of the testtabulated as the percentage improvement of the compounded oils over thereference oil as follows:

As a final test to indicat the eflectiveness of the compounded oilproposed by the present invention, a special endurance test was devisedto test the suitability of the compounded oil. The particular endurancetest which was used was a so-called caterpillar endurance test, whichhas been described in the Diesel Lubricant Test Manual, Laboratory testNo. 1, put out by the Caterpillar Tractor Company. This test was carriedout in a single cylinder Diesel engine operating at 900 R. P. M., with awater jacket temperature of 175 F., running continuously for 1000 hours,or until rings are stuck as indicated by the increase in blowby, and thecrankcase oil drained every sixty hours and fresh oil added thereto.

In the present instance the reference oil used Bearing Oil tested weightRemarks loss Grams 07 975 No. 4 compression ring stuck, oil ring slotsbeginning to collect deposits, and piston partially coated with darkbrown varnish deposit.

Oil rings free, pistons clean, filter virtually free of deposits, andoil ring slots free of deposits. Run was still in progress.

Reference oil 3.0% sulphurized nonglyeeride fat.

0.085 sulphurized nonglyceride fat 0.57,

cal um isoamyl octyl ortho phosphate.

Obviously many modifications and va iations of the invention may be usedwithout departing Reference oil +3.()% I 2. An improved lubricating oiladapted for use in interna1 combustion engines, comprising a ester beingselected from the group consistin of alkyl and naphthenyl esters,together with a sulphurized non-glyceride fat.

3. An improved lubricating oil adapted for use in internal combustionengines, comprising a lubricating oil having incorporated therein 0.05-5.0%, by weight, of polyvalent metal salt of an 0.055.0%, by glyceridefat.

7. An improved lubricating oil adapted for use in internal combustionengines, comprising a tin, antimony, cobalt, zinc, and a sulfurizedfatty material.

8. An improved lubricating oil adapted for use alkyl ester of aphosphorus acid, and 0.05-5.0% by weight of a sulfurized non-glyceridefat.

9. An improved lubricating 011 adapted for use STILES MQXLEY ROBERTS.

